Many scientists contend that release of halogen refrigerants into the atmosphere deleteriously affects the ozone layer that surrounds and protects the earth from ultraviolet solar radiation. Recent international discussions and treaties, coupled with related regulations and legislation, have renewed interest in devices for recovery and storage of used refrigerants from refrigeration systems for later purification and reuse or for proper disposal. U.S. Pat. No. 4,261,178, assigned to the assignee hereof, discloses a refrigerant recovery system in which the inlet of a compressor is coupled through an evaporator and through a manual valve to the refrigeration system from which refrigerant is to be recovered. The compressor outlet is connected through a condenser to a refrigerant storage container. The condenser and evaporator are combined in a single assembly through which cooling air is circulated by a fan. Content of the storage container is monitored by a scale on which the container is mounted for sensing weight of liquid refrigerant in the container, and by a pressure switch coupled to the fluid conduit between the condenser and the container for sensing vapor pressure within the storage container. A full-container condition sensed at the scale or a high-pressure condition sensed at the pressure switch terminates operation of the compressor motor. A vacuum switch is positioned between the inlet valve and the evaporator for sensing evacuation of refrigerant from the refrigeration system and automatically terminating operation of the compressor motor.
U.S. Pat. No. 4,441,330, assigned to the assignee hereof, discloses a system for recovery, purification and recharging of refrigerant in a refrigeration system in which a compressor is connected by solenoid valves through a condenser/evaporator unit and an oil separator to a refrigeration system from which refrigerant is to be recovered, and to a storage tank or container for storing recovered refrigerant. A separate liquid pump is controlled by microprocessor-based electronics to extract refrigerant from the storage container, circulate the refrigerant through a filter and purification unit, and then to recharge the refrigeration system from refrigerant in the purification unit. A separate vacuum pump is connected to the refrigeration system by solenoid valves to evacuate the refrigeration system to atmosphere after recovery of refrigerant therefrom during the refrigerant purification operation.
U.S. Pat. No. 4,688,388, assigned to the assignee hereof, discloses apparatus for service and recharge of refrigeration equipment, with particular application to automotive air conditioning equipment. A vacuum pump, and oil and refrigerant charge containers are housed within a portable enclosure and configured for selective connection by electrically operated solenoid valves to refrigeration equipment under service. The refrigerant and oil containers are carried by a scale that provides electrical output signals as a function of weight of refrigerant and oil remaining in the containers. A microprocessor-based controller receives the scale signals and control signals from an operator panel for automatically cycling through vacuum, oil charge and refrigerant charge stages in a programmed mode of operation. The microprocessor-based controller includes facility for operator programming of the vacuum time and oil and refrigerant charge quantities, and for self- or operator-implemented diagnostics. Operating conditions and stages are displayed at all times to the operator.
U.S. Pat. No. 4,805,416, assigned to the assignee hereof, discloses a system for recovering, purifying and recharging refrigerant in a refrigeration system that includes a refrigerant compressor having an inlet connected through a recovery control valve to a refrigeration system from which refrigerant is to be recovered, purified and recharged. The outlet of the compressor is connected to the first port of a refrigerant storage container, and is operated by an electronic controller in a recovery cycle with the recovery control valve open for extracting refrigerant from the refrigeration system and feeding the refrigerant to the storage container. During a purification cycle, refrigerant is circulated from a second port of the refrigerant storage container in a closed path through a circulation control valve and a filter for removing water and other contaminants, and then returned to the first container port. The refrigeration system from which refrigerant has been recovered is evacuated to atmosphere during a vacuum cycle by means of a vacuum pump connected to the system through a vacuum control valve. The vacuum control valve is opened and the vacuum pump is energized during the vacuum cycle for a predetermine time duration set by the control electronics. Following such evacuation, during a recharging cycle, the second control port of the refrigerant storage container is connected through a recharging valve to the refrigeration system for feeding refrigerant from the storage container to the refrigeration system, and thereby recharging the refrigeration system for normal use.